We can't standardize on RDP because it closes the remote display when we need someone to walk our help desk through what they are experiencing, VNC was hit or miss for features and support when we were looking at products so that wasn't used. pcAnywhere also integrates with our asset management system and help desk; both from Symantec.
> We can't standardize on RDP because it closes the remote display when we need someone to walk our help desk through what they are experiencing
That means you're looking in the wrong place. You don't want Remote Desktop. On Windows XP you want Remote Assistance, and from Windows Vista you want Windows Desktop Sharing. Same underlying protocol, but different semantics -- the session stays open on both ends.